Intrapleural Adenoviral-mediated Endothelial Cell Protein C Receptor Gene Transfer Suppresses the Progression of Malignant Pleural Mesothelioma in a Mouse Model

Our plain-English summary of Intrapleural Adenoviral-mediated Endothelial Cell Protein C Receptor Gene Transfer Suppresses the Progression of Malignant Pleural Mesothelioma in a Mouse Model, by S. Keshava, L.V. Rao, U.R. Pendurthi (Scientific Reports, 2016).

The study

• Authors: S. Keshava, L.V. Rao, U.R. Pendurthi
• Journal: Scientific Reports
• Published: 2016;6:36829
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Malignant pleural mesothelioma (MPM) is an aggressive thoracic cancer with a high mortality rate as it responds poorly to standard therapeutic interventions. Our recent studies showed that expression of endothelial cell protein C receptor (EPCR) in MPM cells suppresses tumorigenicity. The present study was aimed to investigate the mechanism by which EPCR suppresses MPM tumor growth and evaluate whether EPCR gene therapy could suppress the progression of MPM in a mouse model of MPM. Measurement of cytokines from the pleural lavage showed that mice implanted with MPM cells expressing EPCR had elevated levels of IFNγ and TNFα compared to mice implanted with MPM cells lacking EPCR. In vitro studies demonstrated that EPCR expression renders MPM cells highly susceptible to IFNγ + TNFα-induced apoptosis. Intrapleural injection of Ad.EPCR into mice with an established MPM originating from MPM cells lacking EPCR reduced the progression of tumor growth. Ad.EPCR treatment elicited recruitment of macrophages and NK cells into the tumor microenvironment and increased IFNγ and TNFα levels in the pleural space. Ad.EPCR treatment resulted in a marked increase in tumor cell apoptosis. In summary, our data show that EPCR expression in MPM cells promotes tumor cell apoptosis, and intrapleural EPCR gene therapy suppresses MPM progression.

In plain English

This was a laboratory study in cultured human malignant pleural mesothelioma (MPM) cell lines and in nude mice (BALB/c, NU/J) given MPM cells in the pleural cavity. Mice implanted with REN cells transfected to express endothelial cell protein C receptor (EPCR) had a 2 to 3-fold increase in TNF-alpha and IFN-gamma in pleural lavage compared with mice given control-vector REN(z) cells, while IL-6 was reduced. In culture, either cytokine alone caused minimal apoptosis (under 2%), the combination killed about 15 to 20% of REN cells, and about 80% of REN(+EPCR) cells; EPCR knock-down in MS-1 and M9K cells reduced cytokine-induced death. In mice with tumours already established from EPCR-lacking REN cells, repeated intrapleural Ad.EPCR reduced tumour number, volume and burden versus PBS (p less than 0.001) and versus control adenovirus, raised tumour-cell apoptosis from about 10% to roughly 50 to 60%, and increased macrophage and NK-cell infiltration. The authors concluded intrapleural EPCR gene therapy has the potential to slow MPM progression but needs further refinement.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Experimental laboratory study: in vitro cell-culture experiments plus an orthotopic mouse xenograft model of malignant pleural mesothelioma with adenoviral gene transfer
• Who was studied: Human MPM cell lines (REN, REN(+EPCR), MS-1, M9K and their EPCR knock-downs) and nude BALB/c NU/J mice implanted intrapleurally with 1 x 10^6 REN MPM cells; 16-18 mice per group across three independent gene-therapy experiments, and 11 to 15 mice per group in the REN(z) versus REN(+EPCR) cytokine experiment
• Exposure: Intrapleural adenoviral vector encoding human EPCR (Ad.EPCR), 2 x 10^9 particles in 100 microlitres PBS, started on day 11 and repeated every third day for 20 days, compared with GFP control adenovirus and PBS; in vitro treatment with TNF-alpha (10 ng/ml) and/or IFN-gamma (100 U/ml) for 72 h
• Main results:
  • Mice implanted with REN(+EPCR) cells had a 2 to 3-fold increase in pleural lavage TNF-alpha and IFN-gamma compared with mice implanted with REN(z) cells; IL-6 was reduced
  • In vitro, the cytokine combination killed about 80% of REN(+EPCR) cells, versus about 15 to 20% of REN cells; either cytokine alone caused under 2% apoptosis
  • Ad.EPCR-treated mice had significantly lower tumour number, volume and burden than PBS-treated mice, with smaller differences versus control adenovirus
  • Tumour-cell apoptosis by TUNEL staining was about 10% with saline or Ad.Control and approximately 50 to 60% with Ad.EPCR
  • Macrophage infiltration rose from about 5 to 8% (saline or control adenovirus) to greater than 15% with Ad.EPCR, and NK cells from about 1% to about 4%
  • Pleural lavage TNF-alpha and IFN-gamma increased in Ad.EPCR-treated mice but not in saline or control adenovirus groups
• The authors' conclusion: The authors concluded that intrapleural EPCR gene therapy has the potential to slow MPM progression, but that delivery and expression need further refinement; they described the work as proof-of-principle
• Limitations the authors state:
  • The authors stated the replication-deficient adenoviral vector gave only heterogeneous, superficial EPCR expression in tumours, which could explain the incomplete effect on tumour growth
  • The authors stated the study gives no information on which innate immune cell types mediated the antitumour effect, and that the mice used lack T cells so acquired T-cell immunity was not involved
  • The authors stated the mechanism by which EPCR sensitises MPM cells to apoptosis remains unclear and needs a further in-depth study
  • Several supporting observations were reported only as unpublished data not shown in the article

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Cytokine, Apoptosis, Macrophage, Tumor Microenvironment.

Related studies

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• Inhibition of mesothelioma cancer stem-like cells with adenovirus-mediated NK4 gene therapy — X.B. Deng, L. Xiao, et al. (2015)
• Mesenchymal stem cell-mediated delivery boosts the efficacy of suicide gene therapy based on retroviral replicating vectors in peritoneally disseminated cancer — S. Kubo, Y. Takeuchi, et al. (2026)
• Novel orthotopic implantation model of human malignant pleural mesothelioma (EHMES-10 cells) highly expressing vascular endothelial growth factor and its receptor — E. Nakataki, S. Yano, et al. (2006)
• Cyclophosphamide chemotherapy sensitizes tumor cells to TRAIL-dependent CD8 T cell-mediated immune attack resulting in suppression of tumor growth — R.G. van der Most, A.J. Currie, et al. (2009)

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